Stone tool manufacture has not been observed in free-ranging chimpanzees. has been observed in west african chimpanzee groups. has not been observed in any captive nonhuman primate. is uniquely a human characteristic. is common among free-ranging bonobos.

i believe the correct answer from the choices listed above is the first option. the scientists need to look at the   validity of data, claims, hypotheses, and observations before  developing an argument. they base their arguments on facts that are present and they make sure they have proofs. 

explanation:

voluntary muscles are controlled by the cerebellum.

answer; ///segregation;